truth in numbers - 12/16 volt battery Q

Does a 16 volt battery put out 1/3 more than a 12 volt or does a 12 volt put out 25% (1/4) less than a 16 volt?
1/3 of 12 = 4 + 12 = 16
1/4 of 16 = 4 16 - 4 = 12